NIH workshop of ~Current and Emerging Techniques for Monitoring Brain Stucture and Function~, March 28-29, 1996. Consulting with various personnel on the progress/nuances of 2~PE scanning microscopy. Molecular excitation by simultaneous absorption of two or more photons from a strongly focused mode~locked laser provides intrinsically 3~d resolved fluorescence images of specific molecular markers, dynamical records of local calcium ion activity, microneuoropharmacology by local photoactivation of caged bioeffector molecules such as neurotransmitters, quantitative local measures of molecular mobility and a variety of spatially resolvable analytical tools. Penetration depths of optical imaging into neural tissues appear to be substantially enhanced, photodamage and background fluorescence substantially eliminated by non linear microscopy. Principles and properties of the method are summarized and some neuroscience applications illustrated. Invited Lectures and Consultations: Prof. W. W. Webb 2 listings are occasionally listed per page, to save space.